A 5G network, namely, a new radio (NR) network, aims to support higher system performance, including support of different services, different deployment scenarios, and different spectrums. Different services include an enhanced mobile broadband (eMBB) service, a machine type communication (MTC) service, an ultra-reliable and low latency communications (URLLC) service, a Multimedia Broadcast Multicast Service (MBMS), a positioning service, and the like. Different deployment scenarios include an indoor hotspot scenario, a dense urban scenario, a suburban scenario, an urban macro coverage scenario, a high-speed railway scenario, and the like. 5G supports a spectrum range up to 100 gigahertz (GHz), a primary frequency band is lower than or equal to 6 GHz, and a secondary frequency band is higher than 6 GHz.
Different services, different deployment scenarios, and different spectrum have different features, and their respective requirements for system parameters (also referred to as numerology) are different. To support, with high performance, different services, different deployment scenarios, and different spectrum, 5G supports a plurality of sets of system parameters. For example, 5G supports different subcarrier spacings, the different subcarrier spacings are corresponding to different system parameters, and a same subcarrier spacing may support different subframe lengths. Currently, the subframe length may also be referred to as a transmission time interval (TTI) length, or the subframe length may also be referred to as a transmission time unit (TTU) length. A relatively small subframe length such as a subframe length less than 1 millisecond (ms) may be used for a low latency service, for example, URLLC. A relatively large subframe length such as a subframe length of 1 ms may be used for a service whose latency requirement is not high, a service whose data packet size is relatively large, or the like, for example, eMBB.
How to design synchronization signals corresponding to different subframe lengths in a 5G communications network is a problem that needs to be resolved urgently.